U.S. patent number 8,376,349 [Application Number 13/158,557] was granted by the patent office on 2013-02-19 for document feeder, image reader, and image forming apparatus.
This patent grant is currently assigned to Sharp Kabushiki Kaisha. The grantee listed for this patent is Yasumasa Morimoto, Hiroshi Nakatani, Sohichi Takata, Masato Tamehira. Invention is credited to Yasumasa Morimoto, Hiroshi Nakatani, Sohichi Takata, Masato Tamehira.
United States Patent |
8,376,349 |
Morimoto , et al. |
February 19, 2013 |
Document feeder, image reader, and image forming apparatus
Abstract
A document feeder includes a document placing portion, a pick-up
roller, a pair of feed rollers, a pair of registration rollers, a
document sensor, a moving mechanism, and a control portion. The
pick-up roller can move between a sheet feeding position where the
pick-up roller contacts with the upper surface of the document
placed on a placement surface and a standby position where the
pick-up roller does not contact with the upper surface of the
document placed on the placement surface. The document sensor
detects a document between the feed rollers and the registration
rollers in a document feed direction. The moving mechanism moves
the pick-up roller up and down. The control portion moves the
pick-up roller up to the standby position at a timing when the
leading edge of the card document reaches the document sensor in a
card document mode in which card documents are successively
fed.
Inventors: |
Morimoto; Yasumasa (Osaka,
JP), Nakatani; Hiroshi (Osaka, JP),
Tamehira; Masato (Osaka, JP), Takata; Sohichi
(Osaka, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Morimoto; Yasumasa
Nakatani; Hiroshi
Tamehira; Masato
Takata; Sohichi |
Osaka
Osaka
Osaka
Osaka |
N/A
N/A
N/A
N/A |
JP
JP
JP
JP |
|
|
Assignee: |
Sharp Kabushiki Kaisha (Osaka,
JP)
|
Family
ID: |
45095606 |
Appl.
No.: |
13/158,557 |
Filed: |
June 13, 2011 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20110304094 A1 |
Dec 15, 2011 |
|
Foreign Application Priority Data
|
|
|
|
|
Jun 14, 2010 [JP] |
|
|
2010-135490 |
|
Current U.S.
Class: |
271/4.03;
271/4.1; 271/117 |
Current CPC
Class: |
G03G
15/6594 (20130101); H04N 1/0062 (20130101); H04N
1/00702 (20130101); H04N 1/00588 (20130101); B65H
3/0684 (20130101); B65H 9/006 (20130101); B65H
5/062 (20130101); B65H 1/04 (20130101); G03G
15/607 (20130101); B65H 7/02 (20130101); B65H
2701/1914 (20130101); B65H 2511/10 (20130101); G03G
2215/00481 (20130101); H04N 1/00602 (20130101); B65H
2511/414 (20130101); B65H 2405/3322 (20130101); H04N
1/00649 (20130101); B65H 2511/416 (20130101); B65H
2511/10 (20130101); B65H 2220/01 (20130101); B65H
2511/416 (20130101); B65H 2220/03 (20130101); B65H
2511/414 (20130101); B65H 2220/02 (20130101) |
Current International
Class: |
B65H
5/22 (20060101) |
Field of
Search: |
;271/4.03,4.1,10.03,10.11,117,118 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
60-242762 |
|
Dec 1985 |
|
JP |
|
2002-193494 |
|
Jul 2002 |
|
JP |
|
2007-302356 |
|
Nov 2007 |
|
JP |
|
Primary Examiner: McCullough; Michael
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Claims
What is claimed is:
1. A document feeder comprising: a document placing portion having
a placement surface where a document is placed thereon; a pick-up
roller that is adapted to move up and down between a sheet feeding
position in which the pick-up roller contacts with an upper surface
of the document placed on the placement surface and a standby
position in which the pick-up roller does not contact with the
upper surface of the document placed on the placement surface; a
pair of feed rollers and a pair of registration rollers that are
disposed at a downstream side of the pick-up roller in a document
feed direction; a document sensor that detects a document between
the pair of feed rollers and the pair of registration rollers; a
moving mechanism that causes the pick-up roller to move up and
down; an operating portion that receives an operation of selecting
a card document mode in which a plurality of card documents are
successively fed with a predetermined interval between the card
documents and a mode other than the card document mode; and a
control portion that controls the moving mechanism, after the
pick-up roller feeds a card document in a state in which the
pick-up rollers is in the sheet feeding position when the card
document mode is selected in the operating portion, to cause the
pick-up roller to move up to the standby position at any time the
document sensor detects a card document and to move down to the
sheet feeding position when the document sensor detects no card
document.
2. The document feeder according to claim 1, further comprising: a
document size sensor that detects a size of a document placed on
the placement surface, wherein the control portion performs the
card document mode when the document size sensor detects a card
size.
3. The document feeder according to claim 1, further comprising: a
document size sensor that detects a size of a document placed on
the placement surface, wherein the control portion performs the
card document mode when the document size sensor detects a card
size.
4. The document feeder according to claim 1, wherein the standby
position is located above a line that connects a nip portion of the
pair of feed rollers and a nip portion of the pair of registration
rollers.
5. The document feeder according to claim 1, wherein the moving
mechanism includes a motor different from a motor that supplies
rotation to the pick-up roller.
6. The document feeder according to claim 1, wherein the control
portion, when the card document mode is selected in the operating
portion, controls a time from when the document sensor detects the
card document to when the pair of feed rollers stops rotation so
that the time in the card document mode is longer than the time in
the mode other than the card document mode.
7. The document feeder according to claim 1, wherein the control
portion temporarily stops rotation of the feed rollers for a
predetermined period of time when the document sensor detects a
card document.
8. An image reader comprising: the document feeder according to
claim 1; and an image reading portion that is disposed on a
downstream side of the pair of registration rollers in the document
feed direction and that reads image data of the document fed by the
document feeder.
9. An image forming apparatus comprising: the image reader
according to claim 8; and an image forming portion that forms an
image based on image data that the image reading portion reads from
the document.
10. The document feeder according to claim 1, wherein a distance
from a contact position of the pick-up roller in the sheet feeding
position with the card document and to a position of the document
sensor is shorter than a length of the card document in the
document feed direction.
Description
CROSS REFERENCE
This Nonprovisional application claims priority under 35 U.S.C.
.sctn.119(a) on Patent Application No. 2010-135490 filed in Japan
on Jun. 14, 2010, the entire contents of which are hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a document feeder for feeding
documents one by one from a document placing portion to a document
receiving portion via an image reading position, and more
specifically to a document feeder for feeding not only paper
documents having high flexibility but also small-sized card
documents having low flexibility. The present invention also
relates to an image reader and an image forming apparatus provided
with such a document feeder.
2. Description of the Related Art
As a scanner for reading an image of a document, a document feeder
for feeding documents one by one from a document placing portion to
a document receiving portion via an image reading position is used.
Such a document feeder as disclosed in Japanese Patent Laid-Open
Publication No. 60-242762, for example, includes a freely movable
pick-up roller in the upper part of an end portion on the
downstream side of the document placing portion in a document feed
direction, and a pair of feed rollers and a pair of conveyance
roller (hereinafter referred to as a pair of registration rollers,
as the case may be) between the pick-up roller and the document
reading position.
The pick-up roller moves down to a sheet feeding position where the
roller contacts with the upper surface of a document placed on a
document platen while rotating in synchronization with the pair of
feed rollers at start of feeding a document. The pair of feed
rollers rotates while vertically holding the document therebetween.
The pair of conveyance rollers starts rotating after a lapse of
predetermined time from a time when the leading edge of the
document reaches a document sensor disposed on the upstream side of
the pair of conveyance rollers.
The document placed on the document platen is fed toward the pair
of feed rollers by the rotation of the pick-up roller, and then
guided to the pair of conveyance rollers by the rotation of the
pair of feed rollers. The above-stated predetermined time is a time
longer than the time required for the leading edge of a document
sheet to reach the pair of conveyance rollers after having passed
the document sensor. The fed position of the document is corrected
by contacting with the leading edge thereof with the pair of
conveyance rollers before the rollers start rotation.
The document feeder has a space for stacking and placing a
plurality of documents above the document platen so that images on
the plurality of documents are successively read. The pick-up
roller moves up to a standby position which does not contact with
the upper surface of the document placed on the document platen
before starting feeding a document. After moving down to the sheet
feeding position at the start of feeding a document, the pick-up
roller moves up to the standby position when the leading edge of
the document reaches the position of the document sensor.
Images on a plurality of documents being successively read, the
pick-up roller moves up to the standby position every time when the
leading edge of each document reaches the document sensor, and
moves down to the sheet feeding position before feeding the
following document. Such movement of the pick-up roller makes a
larger feeding interval between documents, and lengthens operating
time for feeding a plurality of documents.
In an attempt to overcome such problems, some conventional document
feeders, in successively feeding a plurality of documents, cause a
pick-up roller to move down to a sheet feeding position before
starting feeding the first document, and cause the pick-up roller
to move up to a standby position when the leading edge of the last
document reaches a document sensor. A smaller feeding interval
between documents can shorten time for feeding a plurality of
documents.
In order to correctly read an image of a document in an image
reading position, a document feed path between a feed roller and a
document reading position is formed in a straight line, so that the
nip portion of a pair of registration rollers is located on a line
tangent to the nip portion of a pair of feed rollers. The placement
surface of a document placing portion is located below a straight
line connecting the feed rollers and the image reading position,
and the end portion of the downstream side of the placement surface
is composed of an inclined surface where the downstream side in the
feed direction is located above the upstream side.
In the conventional document feeders, the pick-up roller also moves
up and down in feeding a small-sized card document having low
flexibility at the same timing as in feeding a paper document
having high flexibility. In feeding a plurality of card documents
placed on the document placing portion one by one, the pick-up
roller keeps pressing the card document downward in a sheet feeding
position until the leading edge of the last card document reaches a
sensor position. The card documents other than the last card
document are not guided between the pair of registration rollers
because the leading edge located on the downstream side of the pair
of feed rollers moves upward by being pressed downward on the
upstream side of the pair of feed rollers.
An object of the present invention is to provide a document feeder
capable of surely guiding the leading edge of a card document
between a pair of registration rollers by causing a pick-up roller
to move up to a standby position when the card document is conveyed
at a timing different from when a paper document is conveyed, and
an image reader and an image forming apparatus provided with the
document feeder.
SUMMARY OF THE INVENTION
A document feeder according to the present invention includes a
document placing portion, a pick-up roller, a pair of feed rollers,
a pair of registration rollers, a document sensor, a moving
mechanism, and a control portion. The document placing portion
places a document on a placement surface. The pick-up roller can
move up and down between a sheet feeding position which contacts
with the upper surface of the document placed on the placement
surface and the standby position which does not contact with the
upper surface of the document placed on the placement surface. The
pair of feed rollers and the pair of registration rollers are
disposed at the downstream side of the pick-up roller in a document
feed direction. The document sensor detects a document between the
pair of feed rollers and the pair of registration rollers in the
document feed direction. The moving mechanism causes the pick-up
roller to move up and down. The control portion controls the moving
mechanism so that the pick-up roller is in a standby position at
any time the document sensor detects a card document in a card
document mode in which a plurality of card documents are
successively fed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an image forming apparatus
provided with a document feeder according to an embodiment of the
present invention.
FIG. 2 is a sectional view schematically illustrating the document
feeder and an image reading portion.
FIGS. 3A and 3B are a plan view and a side elevation view of a
moving mechanism of the document feeder.
FIGS. 4A and 4B are figures illustrating operation of the moving
mechanism.
FIG. 5 is a plan view illustrating a neighborhood of a document
placing tray of the document feeder.
FIG. 6 is a block diagram of a control portion of the document
feeder.
FIG. 7 is a plan view of an operating portion of the image forming
apparatus.
FIG. 8 is a timing chart of an operating state of each component by
control of the control portion.
FIGS. 9A to 9F are figures illustrating a state of feeding a card
document in the document feeder.
FIG. 10 is a timing chart of an operating state of each component
by another control of the control portion.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an image forming apparatus provided with a document
feeder according to an embodiment of the present invention is
exemplified and described.
As illustrated in FIG. 1, an image forming apparatus 100 provided
with a document feeder 120 according to an embodiment of the
present invention forms a multi-colored and single-colored image
onto a predetermined sheet (a recording sheet) on the basis of
image data. An image reading portion 90 is disposed on the upper
part of an apparatus main body 110. The document feeder 129 is
attached to the upper side of the image reading portion 90. The
document feeder 120 automatically feeds a document. The document
feeder 120 is pivotally supported at a rear-side end portion
thereof, so that the top surface of the image reading portion 90
can be freely opened and closed.
The apparatus main body 110 includes image forming portions 60A to
60D, an optical scanner 1, an intermediate transfer belt unit 6, a
fixing unit 7, a sheet feeding cassette 81, a copy receiving tray
111 and the like. The image forming portions 60A to 60D form toner
images corresponding to respective hues of yellow, magenta, cyan,
and black. The image forming portion 60A includes a developing
device 2, a photoreceptor drum 3A, a cleaner unit 4, and a charger
5. The image forming portions 60B to 60D respectively have the same
configuration as the image forming portion 60A.
The charger 5 is means for uniformly charging a surface of the
photoreceptor drum 3A to a predetermined potential, and may be a
contact-type charger using a roller or a brush besides the charger
type as illustrated in FIG. 1.
The optical scanner 1 includes semiconductor lasers corresponding
to respective hues of yellow, magenta, cyan, and black, reflection
mirrors, and the like, together with a single polygon mirror. The
optical scanner 1 deflects the laser beams of respective hues
emitted from the semiconductor lasers by the polygon mirror at a
constant angular velocity in the main scanning direction, then
deflects the laser beams by an f-.theta. lens at a constant
velocity, and guides the beams to the respective photoconductor
drums 3A to 3D via the reflection mirrors. The optical scanner 1
may be replaced by a write head having an array of light-emitting
devices such as ELs or LEDs, for example.
The image forming portion 60A forms an electrostatic latent image
on the surface of the photoreceptor drum 3A by the yellow laser
beam emitted from the optical scanner 1. The developing device 2
visualizes an electrostatic latent image formed on the
photoreceptor drum 3A with yellow toner. The cleaner unit 4
collects remaining toner on the surface of the photoreceptor drum
3A after a primary transfer to be described later. Toner images of
magenta, cyan, and black are formed on the respective photoreceptor
drums 3B to 3D in the image forming portions 60B to 60D in the same
manner as in the image forming portion 60A.
The intermediate transfer belt unit 6 includes an intermediate
transfer belt 61, a drive roller 62, an idle roller 63, and an
intermediate transfer roller 64. As for the intermediate transfer
roller 64, four rollers are disposed corresponding to respective
hues of yellow, magenta, cyan, and black.
The drive roller 62, the idle roller 63, and the intermediate
transfer roller 64 stretch the intermediate transfer belt 61
therebetween. By the rotation of the drive roller 62 which receives
a rotational force from a non-illustrated drive source, the
intermediate transfer belt 61 moves along a loop-shaped moving path
passing through the image forming portions 60A to 60D in this
order. The intermediate transfer roller 64 primarily transfers the
toner images on the surface of the photoreceptor drums 3A to 3D on
to the intermediate transfer belt 61 by a transfer bias applied
from a non-illustrated power supply portion.
In full color image formation, the toner images on the surfaces of
the photoconductor drums 3A to 3D are sequentially transferred to
the intermediate transfer belt 61 in an overlaying manner, so that
a color image is formed on the intermediate transfer belt 61 by
subtractive primary colors.
The toner images transferred by the intermediate transfer belt 61
are guided to between the drive roller 62 and a secondary transfer
roller 10 by the rotation of the intermediate transfer belt 61, and
is secondarily transferred on a sheet by the secondary transfer
roller 10. After the secondary transfer, the toner remaining on the
intermediate transfer belt 61 is removed by the cleaning unit
65.
The sheet feeding cassette 81 is disposed below the optical scanner
1, and stores sheets (recording sheets) which are used for image
formation. The manual feed tray 82 is freely rotatably disposed on
one side face of the apparatus main body 110, and places thereon
sheets which are used for the image formation. The copy receiving
tray 111 is disposed above the image forming portions 60A to 60D,
and stores image-formed sheets.
The apparatus main body 110 forms therein a sheet feed path S from
the sheet feed cassette 81 and the manual feed tray 82 to the copy
receiving tray 91 by passing between the intermediate transfer belt
62 and the transfer roller 10 and through the inside of the fixing
unit 7. Along the sheet feed path S, pick-up rollers 11A and 11B,
conveyance rollers 12A to 12D, a registration roller 13, and the
secondary transfer roller 10 are disposed.
The pick-up rollers 11A and 11B are disposed near the sheet feeding
cassette 81 and the manual feed tray 82, respectively, and feed a
sheet one by one from the sheet feeding cassette 81 and the manual
feed tray 82 to the sheet feed path S. The registration roller 13
temporarily holds the sheet conveyed along the sheet feed path S,
and starts rotating at a timing when the leading edge of the sheet
matches the leading edge of the toner image on the intermediate
transfer belt 62 between the intermediate transfer belt 62 and the
secondary transfer roller 10.
The fixing unit 7 includes a heat roller 71 and a pressure roller
72. The heat roller 71 and the pressure roller 72 heat and press
the sheet on which the toner image is secondarily transferred, and
fix the toner image to the sheet.
As illustrated in FIG. 2, the image reader 90 includes document
platens 92 and 93 on an upper surface thereof, and includes a
scanning unit 91 therein. The scanning unit 91 includes mirrors 911
to 914, a lens 915, and a CCD 916, and is made movable back and
forth in parallel to the document platens 92 and 93 under the
document platens 92 and 93. The scanning unit 91 reads an image of
a document manually placed on the document platen 92 while moving
under the document platen 92. The scanning unit 91 also reads an
image of a document fed by the document feeder 120 while resting
under the document platen 93.
The document feeder 120 includes a document placing tray 121, a
pick-up roller 122, a pair of feed rollers 123, a pair of
registration rollers 124, conveyance rollers 125A to 125E, a
document receiving tray 126, and an image reading unit 128. The
document feeder 120 feeds not only highly flexible paper documents
but also low flexible card documents. The card documents include
plastic cards such as IC cards and card-shaped documents such as
driver's licenses, for example.
The document placing tray 121 corresponds to a document placing
portion of the present invention and is designed to allow a
plurality of documents to be placed thereon. The document placing
tray 121 includes a document guide 1211A and a non-illustrated
document guide 1211B which define the position where a document is
to be placed. The end portion on the downstream side in the feed
direction of the document placing tray 121 is composed of an
inclined surface inclined upward to the downstream side.
The pick-up roller 122 is freely movably disposed above the end
portion on the downstream side of the document placing tray 121.
The pick-up roller 122 contacts with the upper surface of documents
placed on the document placing tray 121 in a lower sheet feeding
position, and feeds out the documents one by one toward the pair of
feed rollers 123 by a rotation thereof.
As illustrated in FIGS. 1, 3A, and 3B, the pair of feed rollers 123
and the pair of registration rollers 124 are disposed in this order
on the downstream side of the pick-up roller 122 in the feed
direction. The pair of feed rollers 123 holds the document fed out
by the pick-up roller 122 between nips, and guides the document to
the pair of registration rollers 124 by a rotation thereof. The
pair of registration rollers 124 starts rotating at a timing when
the leading edge of the document reaches the rollers after a lapse
of a predetermined time, holds the document in a nip in a state
where the fed position of the document is corrected, and guides the
document to the document platen 93 by the rotation thereof.
The conveyance rollers 125A to 125D feed a paper document which
passes through the upper surface of the document platen 93 to the
document receiving tray 126. The conveyance roller 125E guides a
card document which passes though the upper surface of the document
platen 93 to an output port 127.
The image reading unit 128 selectively reads an image on a second
face of a sheet whose image on a first face is read by the scanning
unit 91 while passing through the document platen 93. Thus, the
document feeder 120 can read an image on both sides of the document
while feeding the document once from the document placing tray 121
to the document receiving tray 126.
The document feeder 120 includes a moving mechanism 140 illustrated
in FIGS. 3A and 3B. The moving mechanism 140 causes the pick-up
roller 122 to move up and down between an upper standby position
and a lower sheet feeding position. Therefore, the moving mechanism
140 includes a motor 141, a drive gear 142, an idle gear 143, a
rocker arm 144, a support member 145, a photosensor 146, and a
spring 148.
The motor 141 fixes the drive gear 142 on an output shaft rotating
in both forward and reverse directions, and is fixed to a frame 150
of the document feeder 120. The idle gear 143 engages in the drive
gear 142 by being pivotally supported by the frame 150, and
includes, on the side face, a boss 147 which projects in the axial
direction. The idle gear 143 also includes a convex portion 1431
projected from a part of a peripheral direction to a radial
direction. The convex portion 1431 does not interfere with the
drive gear 142. In a plane view illustrated in FIG. 3A, the support
member 145 is U-shaped, and both ends thereof are pivotally
supported by a rotating shaft 131 to which a driving side roller
123A of the pair of feed rollers 123 is fixed. The support member
145 pivotally supports a rotating shaft 134 which fixes the pick-up
roller 122 on the side of an intermediate portion. The photosensor
146 detects the convex portion 1431 of the idle gear 143. The
rocker arm 144 extends upward from the end portion of the support
member 145, and contacts with the peripheral surface of the boss
147 on one side face thereof. The spring 148 has one end engaged in
the frame 150, and biases the rocker arm 144 clockwise around the
rotating shaft 131.
It is to be noted that the rotation from a non-illustrated motor is
transmitted to the rotating shaft 131. The rotation of the rotating
shaft 131 is transmitted to a rotating shaft 134 via a belt 137
stretched over pulleys 135 and 136. Thus, the pick-up roller 122
rotates synchronizing with the drive side roller 123A of the pair
of feed rollers 123.
In addition, the idle side roller 123B of the pair of feed rollers
123 is pivotally supported via a torque limiter 123C. In a case
where a plurality of documents are fed at one time by the pick-up
roller 122, the rotation of the idle side roller 123B stops by
increase in running torque, and only one document which contacts
with the drive side roller 123A passes the pair of feed rollers
123.
In order to move the pick-up roller 122 located in the standby
position shown in FIG. 4A down to the sheet feeding position shown
in FIG. 4B, the motor 141 is driven counterclockwise (the direction
indicated by arrow M). The idle gear 143 rotates clockwise (the
direction indicated by arrow N) and the contact position of the
rocker arm 144 and the boss 147 moves, so that the support member
145 swings clockwise around the rotating shaft 131, and the pick-up
roller 122 moves down together with the rotating shaft 134. While
the pick-up roller 122 is located in the standby position, the
photosensor 146 detects the convex portion 1431. The pick-up roller
122 moves down to the sheet feeding position by driving the motor
141 counterclockwise by a predetermined pulse from a time when the
photosensor 146 has detected the convex portion 1431.
On the contrary, in order to move the pick-up roller 122 located in
the sheet feeding position shown in FIG. 4B up to the standby
position shown in FIG. 4A, the motor 141 is driven clockwise (the
direction indicated by arrow N). The idle gear 143 rotates
counterclockwise (the direction indicated by arrow M), and the
contact position of the rocker arm 144 and the boss 147 moves, so
that the support member 144 swings counterclockwise around the
rotating shaft 131, and the pick-up roller 122 moves up together
with the rotating shaft 134. In this case, the motor 141 is driven
clockwise until the photosensor 146 detects the convex portion.
The moving mechanism 140 includes the motor 141 for causing the
pick-up roller 122 to move up and down in addition to a motor for
rotating the pick-up roller 122 and the pair of feed rollers 123.
Therefore, the moving mechanism can cause the pick-up roller 122 to
move up and down regardless of the rotation state of the pick-up
roller 122 in synchronization with the rotation of the pair of feed
rollers 123.
As shown in FIG. 5, the document feeder 120 pivotally supports an
actuator 152 of a document sensor 151 in a state where a part
thereof exposes in the middle of the feed path, the actuator being
provided between the pair of feed rollers 123 and the pair of
registration rollers 124 in the feed direction (the direction
indicated by arrow X). The actuator 152 rotates in contact with the
leading edge of the document before the edge reaches the pair of
registration rollers 124 after passing the pair of feed rollers
123. The document sensor 151 is composed of a photo coupler as an
example. The end portion of actuator 152 deviates from a light
emitting device and a light receiving device by the rotation of the
actuator 152, whereby the document sensor 151 detects that the
leading edge of the document reaches a nip between the pair of feed
rollers 123 and the pair of registration rollers 124.
The document placing tray 121 includes movable document guides
1211A and 1211B along the direction (the direction indicated by
arrow Y) which intersects perpendicularly with the feed direction
(the direction indicated by arrow X). The document guides 1211A and
1211B define the position where a document is to be placed by
contacting with both side surfaces thereof parallel to the feed
direction of the placed document. The positions of the s 1211A and
1211B are detected by a non-illustrated document size sensor. The
document size sensor detects the size of the document placed on the
document placing tray 121 based on detection result of the
positions of the document guides 1211A and 1211B.
As an example, as shown in FIG. 5, the document guides 1211A and
1211B define the position where a card document is to be placed in
a state where the guides are closest to each other.
At this time, the document size sensor to be described later
detects the size of the card document as a kind of sizes of a
document which is placed on the document placing tray 121.
The document feeder 120 includes a control portion 60 shown in FIG.
6. The control portion 60 is configured to connect a CPU 61 with a
memory 62, a mode switch 63, a document size sensor 64, the
photosensor 146, the document sensor 151, and drivers 65 to 67.
The CPU 61 receives the input of operation signals from the mode
switch 63 and of detection signals from the document size sensor
64, the photosensor 146, and the document sensor 151. The CPU 61
outputs drive data to the drivers 65 to 67 based on these inputted
signals. The drivers 65 to 67 are connected to a motor 68, a motor
141, and a clutch 69, respectively. The motor 68 supplies the
rotation thereof to the rotating shaft 131 of the pair of feed
rollers 123. The motor 141 causes the pick-up roller 122 to move up
and down. The clutch 69 selectively transmits the rotation of the
motor 68 to the pair of registration rollers 124.
The mode switch 63, as shown in FIG. 7 as an example, is displayed
on a display 210 of an operation panel 200 of the image forming
apparatus 100, and receives a selection input by a pressing
operation of a paper document mode switch 631 or a card document
mode switch 632. The CPU 61 performs the card document mode when
the document size sensor 64 detects a card document size or when an
operator presses the card document mode switch 632. The CPU 61
alternatively performs the paper document mode when the document
size sensor 64 detects sizes other than the card document size or
when an operator presses the paper document mode switch 631.
Furthermore, the document size sensor 64 includes a sensor which
detects the positions of the document guides 1211A and 1211B and a
sensor which detects the length of a document in the feed
direction. The sensor which detects the length of a document in the
feed direction is disposed while being exposed to the upper surface
of the document placing tray 121, for example.
As shown in FIG. 8, in feeding a highly flexible paper document in
the paper document mode which successively feeds a plurality of
paper documents (two sheets in FIG. 8), the CPU 61 starts driving
the motor 68 and causes the pick-up roller 122 to move down to the
sheet feeding position. The CPU 61 drives the clutch 69 and starts
rotating the pair of registration rollers 124 at a timing T1 after
a lapse of time required in order to bend a paper document only by
a predetermined amount of resist from an input timing TS of a
detection signal from the document sensor 151. The CPU 61 stops the
rotation of the pair of feed rollers 123 at a timing T2 after a
lapse of time for pressing the leading edge of a paper document
into a nip between the pair of registration rollers 124 only by a
length of 5 mm, for example, from a timing of start of rotation of
the pair of registration rollers 124. The CPU 61 starts driving the
motor 68 for feeding the following paper document (the second paper
document) at a timing T4 when the back end of a preceding paper
document passes the document sensor 151.
In the paper document mode, the CPU 61 causes the pick-up roller
122 to move down to the sheet feeding position until the leading
edge of the last paper document (the 2nd sheet in this example)
placed in the document placing tray 121 is detected by the document
sensor 151. The upstream side of the paper document during being
fed is successively pressed by the pick-up roller 122. Therefore,
even though the rotation of the pair of feed rollers 123 stops
between the timing T2 and the timing T4, the once-fed paper
document does not move back to the document placing tray 121.
In feeding a low flexible card document in the card document mode
which successively feeds a plurality of card documents (two sheets
in FIG. 8), the CPU 61 starts driving the motor 68 and causes the
pick-up roller 122 to move down to the sheet feeding position. The
drive timing of the clutch 69 by the CPU 61 is the same as that in
the paper document mode. The CPU 61 drives the clutch 69 and starts
rotating the pair of registration rollers 124 at the timing T1
after a lapse of time required in order to press a card document
into a nip of the pair of registration rollers 124 only by a
predetermined length from an input timing TS of a detection signal
from the document sensor 151. The CPU 61 also causes the pick-up
roller 122 to move up to the standby position at the timing TS. The
CPU 61 stops the rotation of the pair of feed rollers 123 at a
timing T3 after a lapse of time for pressing the leading edge of a
card document into a nip of the pair of registration rollers 124
only by a length of 50 mm, for example, from a timing of start of
rotation of the pair of registration rollers 124. The CPU 61 starts
driving the motor 68 for feeding the following card document (the
second card document) at the timing T4 when the back end of a
preceding card document passes the document sensor 151.
In the card document mode, the CPU 61 causes the pick-up roller 122
to move up to the standby position every time when the leading edge
of each card document placed in the document placing tray 121 is
detected by the document sensor 151. A card document during being
fed is not pressed by the pick-up roller 122. Therefore, a
sufficiently long time is provided by the timing T4 to prevent the
once-fed card document from moving back to the document placing
tray 121, the timing T3 being a time when the rotation of the feed
rollers 123 stops.
As shown in FIGS. 9A to 9F, a plurality (two sheets) of card
documents D1 and D2 are fed by control in the card document mode by
the CPU 61. More specifically, as shown in FIG. 9A, the pick-up
roller 122 waits for the card documents D1 and D2 to be placed on
the document placing tray 121 in a state where the pick-up roller
122 is located in the standby position.
As shown in FIG. 9C, contacting with the leading edge of the card
document D1 with the actuator 152 causes the pick-up roller 122 to
move up to the standby position. Thereby, the pressing force of the
pick-up roller 122 stops acting on the downstream portion of the
card document D1, and the leading edge of the card document D1, as
shown in FIG. 9D, moves down to the nip position of the pair of
registration rollers 124. The fed position of the card document D1
is surely corrected by contact with the pair of registration
rollers 124 which have not started rotation, so that the leading
edge of the card document D1 can be surely guided to the nip of the
pair of registration rollers 124 which start rotation.
Then, as shown in FIG. 9E, when the leading edge of the card
document D1 passes the nip of the pair of registration rollers 124
about 50 mm, the rotation of the pair of feed rollers 123 and the
pick-up roller 122 stops. When the back end of the card document D1
is detected by the document sensor 151, as shown in FIG. 9F, the
rotation of the pair of feed rollers 123 and the pick-up roller 122
starts, and causes the pick-up roller 122 to move down to the sheet
feeding position to feed the following card document D2.
It is to be noted that the rotation of the pair of registration
rollers 124 stops during time until the leading edge of the card
document D2 reaches the pair of registration rollers 124 after the
back end of the card document D1 passes the pair of registration
rollers 124. This is in order to correct the fed position of the
card document D2 by contacting with the leading edge of the card
document D2 with the pair of registration rollers 124 during
stop.
As shown in FIG. 9A and the like, the standby position of the
pick-up roller 122 is a position where the lower end of the pick-up
roller 122 is located above a line which connects the nip portion
of the pair of feed rollers 123 and the nip portion of the pair of
registration rollers 124. This is because the leading edge of the
card document cannot face the nip of the pair of registration
rollers 124 when the pick-up roller 122 contacts with the end
portion on the downstream side of the card document.
In addition, as shown in FIG. 9C, a distance from a contact
position with the card document in the sheet feeding position of
the pick-up roller 122 to the position of the actuator 152 of the
document sensor 151 is set shorter than the length of the card
document. This is in order to surely detect by the document sensor
151 the leading edge of the card document fed by the pick-up roller
122.
In the control shown in FIG. 8, even after the document sensor 151
detects the leading edge of the card document, the rotation of the
pair of feed rollers 123 continues, and the card document moves
toward the pair of registration rollers 124. Therefore, when the
moving-up speed of the pick-up roller 122 is not high enough as
compared with the feeding speed of the card document by the pair of
feed rollers 123, there is a possibility that the pick-up roller
122 may not separate from the back end portion of the card document
before the leading edge of the card document reaches the pair of
registration rollers 124. In this state, the leading edge of the
card document reaches the pair of registration rollers 124 before
facing the nip portion of the pair of registration rollers 124. Due
to this state, the leading edge of the card document cannot be
guided to the nip of the pair of registration rollers 124.
As a solution to the problem, as shown in FIG. 10, the rotation of
the feed rollers 123 stops from time when the document sensor 151
detects the leading edge of the card document to a timing T5 when a
predetermined time elapses. This predetermined time is determined
in consideration of the time required for the pick-up roller 122 to
move from the sheet feeding position up to the standby
position.
The above embodiments have been described with an image forming
apparatus provided with a document feeder of the present invention.
The document feeder of the present invention, however, can also be
provided with a document reader without an image forming
portion.
The above described embodiments are to be considered in all
respects as illustrative and not restrictive.
The scope of the present invention is defined not by above
described embodiments but by the claims. Furthermore, the scope of
the present invention is intended to include all modifications that
come within the meaning and scope of the claims and any equivalents
thereof.
* * * * *